During a grid fault the grid voltage may decrease. The decreased grid voltage leads to a decrease of the active power generation and consequently to an increase load of the drive train between the rotor and the generator.
In some situations, the wind turbine is required to support the grid by generation and injection of reactive current. The requirement to generate reactive current may contribute with an additional decrease of the active power generation.
Accordingly, it is problem that the wind turbine, particularly the drive train, is exposed to an increased load during fault ride through situations.
WO2015/086022A1 discloses a method for controlling reactive current injection in a wind power plant during a grid fault. The method includes measuring an amount of reactive current to be provided by the wind power plant to the grid during the grid fault. The method further includes determining a difference between a given required reactive current contribution from the wind power plant and the amount of reactive current to be provided by the wind power plant to the grid during the grid fault. The method includes controlling a plurality of wind turbine generators in the wind power plant to generate additional reactive current according to a reactive current reference generated based on the difference.
WO2015/086022A1 does not address load problems during grid faults. Accordingly, there is a need for a technical solution which solves the above mentioned problem.